Angiogenesis, the formation of new blood vessels, is required for the growth of solid tumors and is the major cause of blindness associated with diabetic retinopathy. Vascular endothelial growth factor (VEGF) is believed to be a major stimulant of angiogenesis in these diseases. We propose to use recent advances in DNA binding protein design to create repressor proteins capable of inhibiting VEGF gene expression in vivo. The Phase I goal will be to design proteins that bind adjacent 9 base pair sequences overlapping the transcription start site in the VEGF gene promoter. The DNA binding proteins will be produced and tested for the ability to bind the VEGF target sequences. In Phase II we will design amino acid linkers to join the peptides together to produce a single protein with 18 bp specificity, which should uniquely recognize the VEGF gene promoter. We will determine the ability the individual proteins and the fusion protein to repress VEGF mRNA and protein expression in mammalian cell assays in vitro and in animal tumor models in vivo. This research will lead to the development of novel drugs for treating diseases associated with pathological angiogenesis, including cancer, diabetic retinopathy and inflammation. PROPOSED COMMERCIAL APPLICATION The VEGF repressor proteins we propose to develop will find immediate applications in the treatment of solid tumors, diabetic retinopathy and other diseases associated with pathological angiogenesis. Additionally, the methods proposed for the design of VEGF gene repressors can be applied to any viral or human disease gene target. The success of this project will be a critical proof of principle for "designer repressor" technology. Designer DNA binding proteins and chimeric repressors comprise a new class of therapeutic drugs that potentially could be used to treat a large number of human and viral diseases.